我有一個“完整”的答案在這里以防別人正在尋找這樣的：

#include

#include

....

....

int retVal = -1;

socklen_t retValLen = sizeof (retVal);

int status = connect(socketFD, ...);

if (status == 0)

{

// OK -- socket is ready for IO

}

else if (errno == EINPROGRESS)

{

struct epoll_event newPeerConnectionEvent;

int epollFD = -1;

struct epoll_event processableEvents;

unsigned int numEvents = -1;

if ((epollFD = epoll_create (1)) == -1)

{

printf ("Could not create the epoll FD list. Aborting!");

exit (2);

}

newPeerConnectionEvent.data.fd = socketFD;

newPeerConnectionEvent.events = EPOLLOUT | EPOLLIN | EPOLLERR;

if (epoll_ctl (epollFD, EPOLL_CTL_ADD, socketFD, &newPeerConnectionEvent) == -1)

{

printf ("Could not add the socket FD to the epoll FD list. Aborting!");

exit (2);

}

numEvents = epoll_wait (epollFD, &processableEvents, 1, -1);

if (numEvents < 0)

{

printf ("Serious error in epoll setup: epoll_wait() returned < 0 status!");

exit (2);

}

if (getsockopt (socketFD, SOL_SOCKET, SO_ERROR, &retVal, &retValLen) < 0)

{

// ERROR, fail somehow, close socket

}

if (retVal != 0)

{

// ERROR: connect did not "go through"

}

}

else

{

// ERROR: connect did not "go through" for other non-recoverable reasons.

switch (errno)

{

...

}

}